9 mile tt with 90% of it on fairly rough chipseal. My normal rear wheel is an 808 with Schwalbe Ironman (latex) tubular (23mm) and a wheelcover. TT bike was having rear brake issues and mechanic decided it was too risky to try and run the 808 as it is so wide and the brakes weren't wanting to open that wide so he loaned me his Mavic disc with Tufo (elite?) 21 or 22 tire. So my question is about how much time did I lose using that rear wheel instead of my normal one. I went right at 20 minutes (26.5 mph) This was the tt portion of a stage race and I ended up 3rd GC by 2 seconds--I won the tt but not by as much as I needed. So my question is roughly how much did that combo cost me? I have looked at some of the crr charts and the Tufo tires are pretty much the worst--why does anyone even use them?